JP2018123283A - Laminate comprising cellulose nanofiber-containing support layer, and production method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cellulose nanofiber-containing support layer that is excellent in high-temperature resistance, processability and the like and can be made thinner, a laminate comprising a pressure-sensitive adhesive layer, and a production method thereof.SOLUTION: A laminate comprises a support layer, and pressure-sensitive adhesive layers disposed on one or both faces of the support layer. The support layer contains cellulose nanofiber and has a thickness of 15 μm or less.SELECTED DRAWING: Figure 1

Description

  The present disclosure relates to a laminate including a cellulose nanofiber-containing support layer that is excellent in high-temperature resistance, processability, and the like and can be thinned, and a method for manufacturing the same.

As a base material used for a conventional adhesive tape or the like, a high-quality paper having a weight of 10 g / m ² or more, coated paper, non-woven fabric, and the like were used, and thus the base material itself had a thickness of about 30 μm or more. . However, in recent years, for example, with the trend of downsizing and thinning in the field of electronic components, performance such as thinning is also desired for constituent members such as adhesive tapes used for the components.

  Patent Document 1 (Patent No. 5798980) includes a conductive support base material having a thickness of 1 to 10 μm, which is made of a cured product of a thermosetting resin containing conductive particles, and has conductivity in the thickness direction. Formed on one surface of the conductive support substrate, a first conductive layer having a thickness of 0.01 μm or more and less than 1 μm having conductivity in the plane direction, and formed on the other surface of the conductive support substrate, A second conductive layer having a thickness of 0.01 μm or more and less than 1 μm having conductivity in the plane direction; and a surface of the first conductive layer, including conductive particles having a sphericity of 0.8 or more, and having a thickness A first conductive pressure-sensitive adhesive layer having conductivity in the direction and a surface of the second conductive layer, including conductive particles having a sphericity of 0.8 or more, and having conductivity in the thickness direction. A conductive pressure-sensitive adhesive sheet having two conductive pressure-sensitive adhesive layers is described.

Japanese Patent No. 5798980

  Conventional means for thinning the pressure-sensitive adhesive tape are as follows: (1) means for using only the pressure-sensitive adhesive layer without using the base material itself, (2) means for using a resin base material such as thin PET, (3) thinning Means using fiber base materials such as non-woven fabrics have been adopted. However, in the case of (1), since the pressure-sensitive adhesive layer is not supported by the base material, for example, there is a problem that cutting such as die cutting is difficult. In the case of (2), since a thin resin base material such as PET is used, there is a problem that the base material contracts when the adhesive tape undergoes a heating process. In addition, in the case of (3), it is difficult to obtain a fiber base material of about 15 μm or less in production, and when the fiber base material is formed of resin fibers, Similarly, there was a problem of shrinkage in the heating process.

  The present disclosure provides a laminate including a cellulose nanofiber-containing support layer and a pressure-sensitive adhesive layer that are excellent in high-temperature resistance, processability, and the like and can be thinned, and a method for producing the same.

  According to one embodiment of the present disclosure, a laminate comprising a support layer and an adhesive layer disposed on one or both sides of the support layer, the support layer including cellulose nanofibers, and about A laminate having a thickness of 15 μm or less is provided.

  According to another embodiment of the present disclosure, there is provided a manufacturing method of the above laminate, the step of applying a pressure-sensitive adhesive solution to a release substrate and drying to form a pressure-sensitive adhesive layer; A step of applying a support layer constituting liquid and drying to form a support layer, and optionally, applying a pressure-sensitive adhesive solution on the support layer and drying to form a pressure-sensitive adhesive layer. A method of manufacturing a body is provided.

  According to still another embodiment of the present disclosure, there is provided a manufacturing method of the above-described laminate, in which a pressure-sensitive adhesive solution is applied to a first release substrate and dried, and a first release group including a pressure-sensitive adhesive layer is provided. A step of forming a material, and applying and drying a support layer constituent liquid on the second release substrate to form a second release substrate provided with the support layer, or sticking to the second release substrate A pressure-sensitive adhesive solution is applied and dried to form a pressure-sensitive adhesive layer, and a support layer constituent liquid is applied and dried on the pressure-sensitive adhesive layer to form a second release substrate including the pressure-sensitive adhesive layer and the support layer. There is provided a method for producing a laminate, comprising: a step, and a step of bonding a pressure-sensitive adhesive layer of a first release substrate and a support layer of a second release substrate.

  The laminate of the present disclosure is excellent in high temperature resistance, processability, and the like, and can be thinned.

  For example, when the support layer and / or the pressure-sensitive adhesive layer contains a conductive filler, the laminate of the present disclosure is excellent in electrical grounding property in addition to the above performance.

  In the method for producing a laminate of the present disclosure, a thin support layer of about 15 μm or less can be formed by a coating unit, and thus, for example, curling that occurs when a metal foil is used as the support layer can be reduced. Compared to the case where a thin resin film or the like is used as a support layer, problems such as cutting, cracking, and wrinkling of the support layer can be reduced. Are better.

  The above description should not be construed as disclosing all embodiments of the present disclosure and all advantages related to the present disclosure.

It is the schematic which shows the laminated body by one embodiment of this indication. It is the schematic of the resistivity measurement test of the laminated body by one embodiment of this indication.

  The laminate in the first embodiment includes a support layer and a pressure-sensitive adhesive layer disposed on one or both sides of the support layer, the support layer includes cellulose nanofibers, and has a thickness of about 15 μm or less. Have. The support layer containing cellulose nanofiber has high strength, can support the pressure-sensitive adhesive layer even when the thickness is about 15 μm or less, and is excellent in workability such as cutting. A support layer containing cellulose nanofibers can reduce shrinkage associated with high-temperature processing such as solder reflow processing.

  The support layer of the laminate in the first embodiment can further contain a binder resin. When the support layer contains a binder resin in addition to cellulose nanofibers, cracks in the support layer can be prevented.

  The support layer and / or the pressure-sensitive adhesive layer of the laminate in the first embodiment may include a filler such as a conductive filler. When the support layer and the pressure-sensitive adhesive layer contain a filler, performances such as electrical grounding property and strength of the laminate can be further improved.

  The manufacturing method of the laminated body in 1st Embodiment apply | coats a support layer constituent liquid on the process of apply | coating an adhesive solution to a peeling base material, making it dry and forming an adhesive layer, and an adhesive layer, A step of drying to form a support layer, and optionally a step of applying a pressure-sensitive adhesive solution on the support layer and drying to form a pressure-sensitive adhesive layer.

  Another manufacturing method of the laminated body in 1st Embodiment is the process of apply | coating an adhesive solution to a 1st peeling base material, making it dry, and forming the 1st peeling base material provided with an adhesive layer, The support layer constituent liquid is applied to the release substrate 2 and dried to form a second release substrate having the support layer, or the adhesive solution is applied to the second release substrate and dried. Forming a pressure-sensitive adhesive layer, applying a support layer constituting liquid on the pressure-sensitive adhesive layer and drying to form a second release substrate including the pressure-sensitive adhesive layer and the support layer; and the first step A step of bonding the pressure-sensitive adhesive layer of the release substrate and the support layer of the second release substrate.

  In these production methods, a thin support layer of about 15 μm or less can be formed by a coating means, so that, for example, curling that occurs when a metal foil is used as the support layer can be reduced, and a thin film form is also possible. Compared to the case of using a resin film as a support layer, it is possible to reduce defects such as cutting, cracks, wrinkles, etc. of the support layer. Yes.

  Hereinafter, the present disclosure will be described in more detail for the purpose of illustrating representative embodiments of the present disclosure, but the present disclosure is not limited to these embodiments.

  In the present disclosure, “(meth) acryl” means acryl or methacryl, and “(meth) acrylate” means acrylate or methacrylate.

  In the present disclosure, “glass transition temperature (Tg)” means −80 ° C. to 300 ° C. at a rate of temperature increase of 5 ° C./min in a shear mode of 2% shear strain and a frequency of 1.0 Hz in a viscoelasticity measuring apparatus. This is a temperature at which the loss tangent tan δ is measured in the temperature range of ° C. and shows the maximum tan δ.

  In the present disclosure, the “weight average molecular weight” is a polystyrene equivalent weight average molecular weight measured by gel permeation chromatography (GPC).

  The laminate of one embodiment of the present disclosure includes a support layer and an adhesive layer disposed on one or both sides of the support layer, the support layer includes cellulose nanofibers, and has a thickness of about 15 μm or less. Have

Adhesive layer The (meth) acrylic polymer used in the adhesive layer of the present disclosure is a (meth) acrylic copolymer obtained by copolymerizing a mixture containing the monomer (a) and the monomer (b) shown below. It is a polymer.

  Examples of the monomer (a) having a radical polymerizable unsaturated group and having at least one reactive functional group include (meth) acrylic acid, β-carboxyethyl acrylate, itaconic acid, crotonic acid, Monomers containing carboxyl groups such as fumaric acid, fumaric anhydride, maleic acid, maleic anhydride, butyl maleate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (Meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 8-hydroxyoctyl (meth) acrylate, 10-hydroxydecyl (meth) acrylate, 12-hydroxylauryl (meth) acrylate, (4-hydroxymethylhexyl) -methyl Acrylate, chloro-2-hydroxypro Le (meth) acrylate, diethylene glycol mono (meth) acrylate, caprolactone-modified (meth) acrylates, polyethylene glycol (meth) acrylates include monomers containing a hydroxyl group such as polypropylene glycol (meth) acrylates. Monomers containing amino groups such as aminomethyl (meth) acrylate, monomers containing amide groups such as acrylamide, monomers containing maleimide groups such as N-cyclohexylmaleimide, N-methylitaconimide, etc. Or a monomer containing an itaconimide group, a monomer containing a succinimide group such as N- (meth) acryloyloxymethylene succinimide, or a monomer containing an epoxy group such as glycidyl (meth) acrylate. It is done. These can be used alone or in combination. The amount used is about 0.01% by mass or more, about 0.1% by mass or more, or about 1% by mass or more, about 20% by mass or less, about 17% by mass or less, or about 15% by mass with respect to the total amount of monomers. % Or less. When the amount of the monomer (a) used is within this range, foaming and peeling can be prevented in a heating environment, and sufficient adhesive strength can be exhibited.

  Examples of the monomer (b) other than the monomer (a) include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, n-butyl (meth) acrylate, and isobutyl (meth) acrylate. , 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, isononyl (meth) acrylate, cyclohexyl (meth) acrylate, benzyl (meth) ) Acrylate, methoxyethyl (meth) acrylate, ethoxyethyl (meth) acrylate, phenoxyethyl (meth) acrylate, and other (meth) acrylic acid esters. The amount used is about 80% by mass or more, about 83% by mass or more, or about 85% by mass or more, about 99.99% by mass or less, about 99.9% by mass or less, or about 99% by mass with respect to the total amount of monomers. % Or less. These monomers (b) can be used alone or in combination.

  A monomer (c) other than the monomers (a) and (b), which is copolymerizable with the monomers (a) and (b), may optionally be used. Examples of the monomer (c) include vinyl acetate, styrene, methyl styrene, vinyl toluene, acrylonitrile and the like. The monomer (c) can be used in a range of about 20% by mass or less based on the total amount of monomers.

  When the laminate of the present disclosure requires heat resistance, the pressure-sensitive adhesive layer preferably contains a (meth) acrylic polymer having a glass transition temperature (Tg) of about −50 ° C. or more and about 50 ° C. or less. When the glass transition temperature (Tg) is within this range, the pressure-sensitive adhesive layer of the present disclosure can exhibit high cohesion and appropriate cohesive force and heat resistance.

  The pressure-sensitive adhesive layer of the present disclosure may include a (meth) acrylic polymer having a weight average molecular weight of about 1 million or more. When the weight average molecular weight is within this range, foaming and peeling caused by insufficient cohesive force can be prevented. From the viewpoint of workability such as coating with an increase in the viscosity of the pressure-sensitive adhesive, the weight average molecular weight of the (meth) acrylic polymer may be about 2.5 million or less or about 2 million or less.

  The pressure-sensitive adhesive layer containing the (meth) acrylic polymer having a glass transition temperature (Tg) and a weight average molecular weight within the above range is not less than about 240 ° C., particularly about 260 ° C. in the solder reflow process. The cohesive force can be maintained.

  The pressure-sensitive adhesive layer of the present disclosure can be mixed with a tackifier resin for the purpose of adjusting the tackiness. Examples of the tackifying resin to be blended include rosin-based tackifying resins, terpene-based tackifying resins, petroleum-based tackifying resins, coal-based tackifying resins, and other known tackifying resins. These tackifier resins can be used alone or in combination. The tackifying resin may be used in a range of about 0.5 parts by weight or more or about 1 part by weight or more, about 100 parts by weight or less or about 50 parts by weight or less with respect to 100 parts by weight of the (meth) acrylic polymer. it can.

  The pressure-sensitive adhesive layer of the present disclosure can contain a polyfunctional compound as a crosslinking agent. The functional group of the polyfunctional compound reacts with the functional group having reactivity included in the monomer (a) having at least one functional group in addition to the radical polymerizable unsaturated group. And has at least 2, preferably 2 to 4, functional groups in one molecule. Examples of such polyfunctional compounds include isocyanate compounds, epoxy compounds, amine compounds, metal chelate compounds, aziridine compounds, and the like. When a carboxyl group is contained in the (meth) acrylic polymer, heat resistance can be particularly improved by using an epoxy compound among these crosslinking agents.

  The crosslinking agent is used in a range of about 0.05 parts by weight or more and about 10 parts by weight or less with respect to 100 parts by weight of the (meth) acrylic polymer. By using a crosslinking agent in such an amount, a suitable three-dimensional crosslinking is formed in the (meth) acrylic polymer, and excellent heat resistance can be exhibited. The above crosslinking agents can be used alone or in combination.

  Any known method can be employed for producing the (meth) acrylic polymer contained in the pressure-sensitive adhesive layer used in the present disclosure. For example, a (meth) acrylic polymer is bulk polymerization, solution polymerization, emulsion polymerization, suspension using about 0.001 part or more and about 5 parts or less of a polymerization initiator with respect to 100 parts by weight of the raw material monomer. It can be synthesized by a method such as turbid polymerization.

  The pressure-sensitive adhesive layer of the present disclosure can be filled with a filler (filler) such as a conductive filler and a heat conductive filler, a silane coupling agent, a plasticizer, a pigment, a dye, a flame retardant, an antioxidant, and an ultraviolet absorber as necessary. An agent, a stabilizer, etc. can be blended.

  The thickness of the pressure-sensitive adhesive layer of the present disclosure can be appropriately determined according to the use application of the laminate, and is not limited to the following, but is about 5.0 mm or less, about 4.0 mm or less, or about 3. It may be 0 mm or less. For example, when used for a thin electric component or the like, the thickness may be about 20 μm or less, about 15 μm or less, or about 10 μm or less. The lower limit of the pressure-sensitive adhesive layer is not particularly limited, but can be about 0.5 μm or more, about 1.0 μm or more, or about 1.5 μm or more.

Support Layer The support layer of the present disclosure includes cellulose nanofibers and has a thickness of about 15 μm or less. Although various things can be used as a cellulose nanofiber, the manufacturing method of a cellulose nanofiber etc. are demonstrated below as an example.

(material)
A cellulose material is used as a raw material for cellulose nanofibers. The cellulose material may be subjected to pretreatment such as pulverization, explosion, swelling, purification, bleaching, dissolution regeneration, and alkali treatment. In particular, as a cellulose material, it is preferable to use naturally derived cellulose having a crystal structure of cellulose I when a strong coating film or the like is obtained. Examples of cellulose used as a raw material include wood pulp, non-wood pulp, cotton pulp, bacterial cellulose, squirt cellulose, and waste paper.

(Method of introducing carboxyl group)
As a method for introducing a carboxyl group into cellulose, a generally known chemical modification method can be used. As known in carboxymethylation, a method of introducing a carboxyl group by esterifying and etherifying a hydroxyl group of cellulose, a method of introducing a carboxyl group from a hydroxyl group by an oxidation reaction, and the like can be selected. In the case of introducing a carboxyl group without destroying the crystal structure, a method using a nitroxy radical derivative as a catalyst and using a hypohalite, a halite or the like as a co-oxidant is preferable. In particular, TEMPO (2,2,6,6-tetramethylpiperidinooxy radical) is used as a catalyst and contains sodium hypochlorite and sodium bromide under alkaline conditions, preferably in the range of pH 9 or more and pH 11 or less. The TEMPO oxidation method carried out in an aqueous medium is preferred from the viewpoint of availability of reagents, cost, and reaction stability. In the TEMPO oxidation method, since alkali is consumed as the reaction proceeds, an aqueous alkali solution can be added as needed to keep the pH in the system constant.

  In TEMPO oxidation, the 6-position hydroxyl group of the pyranose ring (glucose) of the cellulose molecule is selectively oxidized, and a carboxyl group can be introduced via an aldehyde group. In TEMPO oxidation using natural cellulose, oxidation occurs only on the surface of crystalline microfibril, which is a structural unit of cellulose, and oxidation does not occur inside the crystal. For this reason, fine cellulose fibers can be obtained while maintaining the crystal structure of cellulose I, and the fine cellulose fibers to be produced have characteristics such as high heat resistance, low linear expansion coefficient, high elastic modulus, and high strength.

  A commercially available thing can be used for the reagents used for TEMPO oxidation. When the reaction temperature is about 0 ° C. or more and about 60 ° C. or less and the reaction time is about 1 hour or more and about 12 hours or less, fine fibers are formed, and a sufficient amount of carboxyl groups can be introduced to show dispersibility. TEMPOs and sodium bromide need only be used in a catalytic amount during the reaction, and can also be recovered after the reaction. In the above reaction system, sodium chloride is the only theoretical by-product, and the treatment of the waste liquid is easy and the burden on the environment is small.

  The amount of the carboxyl group can be adjusted by appropriately setting the TEMPO oxidation conditions. For example, cellulose fibers can be dispersed in an aqueous medium by an electric repulsive force of a carboxyl group through a dispersion treatment step described later. From the viewpoint of dispersibility in an aqueous medium, the carboxyl group content is about 0.1 mmol / g or more, about 0.6 mmol / g or more, about 5.5 mmol / g or less, about 3.5 mmol / g or less. Alternatively, it can be about 2.5 mmol / g or less. In the process of introducing the carboxyl group, an aldehyde group that is an intermediate of the oxidation reaction is generated, and the aldehyde group may remain in the final product. From the viewpoint of dispersibility in an aqueous medium, discoloration of the film, and the like, the aldehyde group content may be about 0.3 mmol / g or less.

  The oxidation reaction is stopped by adding an excessive amount of other alcohol to completely consume the cooxidant in the system. As the alcohol to be added, it is desirable to use a low molecular weight alcohol such as methanol, ethanol or propanol in order to quickly terminate the reaction. Among these, ethanol is preferable in consideration of safety and by-products generated by oxidation.

(Recovery of oxidized cellulose)
After the oxidation reaction is stopped, the produced oxidized cellulose can be recovered from the reaction solution by filtration. In the oxidized cellulose after the reaction is stopped, the carboxyl group may form a salt having a counter ion of a metal ion derived from a co-oxidant or an inorganic alkali for pH adjustment. As a recovery method, a method in which the carboxyl group is filtered while forming a salt, a method in which an acid is added to the reaction solution and the pH is adjusted to 3 or less to filter it out as a carboxylic acid, and an organic solvent is added to cause aggregation. There is another way. Among these, from the viewpoint of handling properties, yield, and waste liquid treatment, a method of converting to carboxylic acid and collecting it is preferable. Also in the preparation of the fine cellulose fiber composition described below, a method in which a metal ion is not contained as a counter ion is excellent in miscibility with a solvent, and therefore, a method of converting it to a carboxylic acid and recovering it is preferable.

  The metal ion content contained in the oxidized cellulose can be examined by various analysis methods. For example, it can be examined by elemental analysis such as EPMA method using an electron beam microanalyzer or X-ray fluorescence analysis. When recovered by the method of filtering while forming a salt, the content of metal ions is 5% by mass or more, whereas when recovered by the method of filtering after being carboxylic acid, the content of metal ions is It can be 1 mass% or less. In particular, when the oxidized cellulose is washed by the following method, the metal ion content can be made below the detection limit.

(Washing)
The recovered oxidized cellulose can be purified by repeated washing with water or the like, and residues such as sodium chloride and ions that are catalysts and by-products can be removed. At this time, after washing with a cleaning liquid adjusted to an acidic condition of pH 3 or less, preferably pH 1.8 or less using hydrochloric acid or the like, and then washing with water, the metal ions are reduced below the detection limit in the above analytical method. be able to. In order to further reduce the amount of remaining metal ions, washing under acidic conditions may be performed a plurality of times.

Next, a process for dispersing cellulose oxide and preparing a cellulose nanofiber dispersion will be described.
(Dispersion process)
As a step of refining the washed oxidized cellulose, first, the oxidized cellulose is immersed in an aqueous medium that is a dispersion medium. At this time, the pH of the immersed liquid is, for example, 4 or less. Oxidized cellulose is insoluble in an aqueous medium and becomes a non-uniform suspension when immersed.

  In the oxidized cellulose suspension, the solid content concentration of the oxidized cellulose is preferably about 10% by mass or less or about 5% by mass or less from the viewpoint of dispersibility, transparency and the like. The minimum of solid content concentration is not specifically limited, What is necessary is just more than 0 mass%.

  Next, the pH of the oxidized cellulose suspension is adjusted to a range of 4 or more and 12 or less using an alkali. In particular, when the pH is set to alkalinity of 7 or more and 12 or less and a carboxylate is formed, electrical repulsion between carboxyl groups is likely to occur, so that dispersibility is improved and cellulose nanofibers are easily obtained.

The type of alkali is not limited, and an inorganic alkali such as sodium hydroxide, lithium hydroxide, or potassium hydroxide can be used. Alternatively, the pH can be adjusted using ammonia water or organic alkali. Organic alkalis include various aliphatic amines, aromatic amines, amines such as diamines, tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetra-n-butylammonium hydroxide, benzyltrimethylammonium hydroxide, 2-hydroxyhydroxide. A hydroxide ion represented by NR ₄ OH (R is an alkyl group, a benzyl group, a phenyl group, or a hydroxyalkyl group, and four Rs may be the same or different) such as ethyltrimethylammonium, etc. Organic onium compounds having a hydroxide ion as a counter ion such as a quaternary ammonium compound, a phosphonium hydroxide compound such as tetraethylphosphonium hydroxide, an oxonium hydroxide compound, and a sulfonium hydroxide compound.

  When using an organic alkali as the alkali, the dispersion treatment can be performed in a shorter energy and in a shorter time than when an inorganic alkali having a metal ion as a counter ion is used, and the transparency of the finally reached dispersion is also improved. high. This is presumably because the use of organic alkali has a larger effect of separating cellulose nanofibers in the dispersion medium because the ion diameter of the counter ion is larger.

  When an organic alkali is used, since it has a high affinity for an organic solvent, a cellulose nanofiber dispersion can be prepared even when an organic solvent such as alcohol is used as a dispersion medium. It is also possible to add an organic solvent after the dispersion treatment to the cellulose nanofiber dispersion dispersion-treated in an aqueous medium. Examples of the aqueous medium include water or a mixed solvent of water and an organic solvent. Examples of the organic solvent include alcohols such as methanol, ethanol and 2-propanol (IPA), ketones such as acetone and methyl ethyl ketone (MEK), ethers such as 1,4-dioxane and tetrahydrofuran (THF), N, N -Dimethylformamide (DMF), N, N-dimethylacetamide (DMAc), dimethyl sulfoxide (DMSO), acetonitrile, ethyl acetate, glycerin and the like. Any one of these may be used alone, or two or more mixed solvents may be used.

  As the method for dispersing the oxidized cellulose suspension, various known dispersion treatments can be used. For example, homomixer processing, mixer processing with rotary blade, high pressure homogenizer processing, ultra high pressure homogenizer processing, ultrasonic homogenizer processing, nanogenizer processing, disc type refiner processing, conical type refiner processing, double disc type refiner processing, grinder processing, ball mill processing There are kneading treatment with a biaxial kneader, underwater facing treatment, and the like. It is possible to combine two or more of these processes. Among these processes, a mixer process with a rotary blade, a high-pressure homogenizer process, an ultra-high pressure homogenizer process, and an ultrasonic homogenizer process are preferable from the viewpoint of miniaturization efficiency.

  When the dispersion treatment is performed, the oxidized cellulose suspension becomes a transparent dispersion that is visually uniform. Oxidized cellulose is refined by dispersion treatment to form cellulose nanofibers. The number average fiber diameter (width in the minor axis direction of the fiber) of the cellulose nanofiber after the dispersion treatment is about 0.001 μm (1 nm) or more, about 0.500 μm (500 nm) or less, about 0.200 μm (200 nm) or less. Alternatively, it can be about 0.050 μm (50 nm) or less. The number average fiber diameter of the cellulose nanofibers can be confirmed by a scanning electron microscope (SEM), an atomic force microscope (AFM), or the like.

  As a coating liquid containing cellulose nanofibers having a carboxyl group produced by the above method or the like, the cellulose nanofiber dispersion liquid can be used as a coating liquid as it is, but a known binder resin, the above-described solvent, etc. It may be added. Moreover, the cellulose nanofiber which has the carboxyl group manufactured by said method etc. is isolated, well-known binder resin, the above-mentioned solvent, etc. may be mixed, and a coating liquid may be prepared separately.

  As the binder resin, urethane resin, (meth) acrylic resin, epoxy resin and the like can be used, and known plasticizers such as adipic acid ester and low molecular weight polyester are also used as a kind of binder resin. Can do. As the binder resin, water-soluble, water-dispersible, and solvent-based ones can be appropriately used depending on the type of dispersion medium of the cellulose nanofiber dispersion. The use of a binder resin is preferable because, for example, the generation of cracks accompanying the shrinkage of cellulose nanofibers during drying can be reduced. Since the plasticizer has an effect of improving the slip of the cellulose nanofiber, it is considered that the nanofiber can follow the shrinkage at the time of drying to reduce cracks in the support layer.

  When the binder resin is used, the weight ratio between the cellulose nanofibers and the binder resin is 10/90 or more, 50/50 or more, 99/1 in terms of solid content in consideration of the strength of the support layer, crack reduction, and the like. Or within a range of 90/10 or less.

  The support layer of the present disclosure may be made of a filler (filler) such as a conductive filler or a heat conductive filler, a silane coupling agent, a pigment, a dye, a flame retardant, an antioxidant, an ultraviolet absorber, and a stabilization, as necessary. An agent or the like can be blended.

  Since the support layer includes cellulose nanofibers and is excellent in strength and the like, the thickness of the support layer to which the pressure-sensitive adhesive layer is applied can be about 15 μm or less, about 13 μm or less, or about 10 μm or less. The lower limit of the thickness of the support layer is not particularly limited, but can be about 0.5 μm or more, about 1.0 μm or more, or about 1.5 μm or more.

  When considering use in applications where thinness is required, the total thickness of the laminate including the support layer and the pressure-sensitive adhesive layer excluding the thickness of the release substrate is about 1 μm or more, about 2 μm or more, or about It can be 3 μm or more, about 50 μm or less, about 40 μm or less, or about 30 μm or less.

Manufacturing method of laminated body The laminated body of this indication can be manufactured as follows, for example.

  At least one surface of the pressure-sensitive adhesive solution containing the above-mentioned (meth) acrylic polymer, a solvent such as ethyl acetate, toluene, or methyl ethyl ketone, and, if necessary, an additive such as a tackifier, a filler, or a crosslinking agent, was subjected to a release treatment. A pressure-sensitive adhesive layer is formed by applying and drying on a release treatment surface of a known release substrate by die coating, knife coating, bar coating, gravure coating, notch bar coating (comma coating) or other well-known conventional application methods. To do. Next, the above-mentioned cellulose nanofiber, a solvent such as water and methanol, and if necessary, a support layer constituting liquid containing a binder resin, a filler, and the like are coated on the formed adhesive layer with knife coating, notch bar coating (comma coating), It can be applied and dried by die coating, bar coating, gravure coating or other known and commonly used coating methods to form a support layer, and a laminate having an adhesive layer on one side can be obtained. When obtaining a laminate having an adhesive layer on both sides as shown in FIG. 1, the adhesive solution is further applied to the formed support layer and dried to form an adhesive layer. What is necessary is just to further apply a peeling base material to an adhesive layer. According to this method, since a laminated body can be obtained continuously in one pass, the manufacturing efficiency is excellent. A method is also conceivable in which a thin support film having a thickness of 15 μm or less is prepared and bonded to the pressure-sensitive adhesive layer. In such a case, the thin support film may be damaged during the production, and the production efficiency is reduced. May decrease. Also, compared to the case where such a support film is bonded to the pressure-sensitive adhesive layer to form a laminate, a support layer constituting liquid containing cellulose nanofibers is applied on the pressure-sensitive adhesive layer, and in particular, a shearing force is easily applied. When applied by knife coating or notch bar coating (comma coating), a mixed region of the components constituting the pressure-sensitive adhesive layer and the components constituting the support layer is formed at the interface between the pressure-sensitive adhesive layer and the support layer. And / or a region where cellulose nanofibers are pierced into the flexible adhesive layer, the adhesion between the adhesive layer and the support layer is improved, and it is difficult to peel off, such as punching, cutting, etc. Workability is also improved. When the pressure-sensitive adhesive contains a cross-linking agent, the pressure-sensitive adhesive layer is cured after the support layer is applied to the pressure-sensitive adhesive layer and then the pressure-sensitive adhesive layer is applied to the support layer in consideration of the ease of formation of the region. It is preferable. According to the production method of the present disclosure, sufficient interlayer adhesion can be obtained by forming the above region. Therefore, a special functional group for reacting with cellulose nanofibers to improve adhesion is adhered by modification treatment or the like. It is not necessary to give separately to the agent component.

  The laminated body of this indication can also be manufactured as follows.

  A pressure-sensitive adhesive solution containing the above-mentioned (meth) acrylic polymer, a solvent such as ethyl acetate, toluene, or methyl ethyl ketone, and, if necessary, an additive such as a tackifier, a filler, or a cross-linking agent is formed on a first release substrate. It is applied and dried by coating, knife coating, bar coating, gravure coating, notch bar coating (comma coating) or other well-known conventional application methods to form a first release substrate having an adhesive layer. Next, the second release substrate is coated with the above-mentioned cellulose nanofiber, a solvent such as water and methanol, and, if necessary, a support layer constituting liquid containing a binder resin, a filler and the like by knife coating, notch bar coating (comma coating), It is applied and dried by die coating, bar coating, gravure coating or other well-known conventional application methods to form a second release substrate with a support layer, or the adhesive solution is applied to the second release substrate as described above The coating method is applied and dried to form a pressure-sensitive adhesive layer, and the support layer constituent liquid is applied and dried on the pressure-sensitive adhesive layer by using the above-described coating method to form the pressure-sensitive adhesive layer and the support layer. The 2nd peeling base material provided is formed. By laminating the obtained pressure-sensitive adhesive layer of the first release substrate and the support layer of the second release substrate, a laminate can be formed.

  Since the support layer constituting liquid containing cellulose nanofibers used in the above-described method is excellent in thixotropy, it can maintain a high viscosity state even if the solid content is low. In the case of general coating liquids containing resins and solvents, if the solid content is low, the viscosity of the coating liquid also decreases at the same time, so gravure coating, knife coating, notch bar coating (comma coating) ) And the like, and it was difficult to uniformly form a thin support layer having a thickness of 15 μm or less by the coating means. In particular, when a filler, especially a filler having a specific gravity greater than about 1, such as about 2 or more, about 3 or more, or about 5 or more, is blended with a low solid content, low viscosity coating liquid, the filler is easy. It was even more difficult to apply such a coating solution uniformly. On the other hand, since the support layer constituting liquid containing cellulose nanofibers has a high viscosity even if the solid content is low, the filler can be dispersed without being precipitated in the coating liquid. As a result, a thin support layer of about 15 μm or less can be uniformly formed even with a low solid content coating liquid containing a filler. In the case of the support layer constituting liquid containing such a filler, it is preferable to use knife coating or notch bar coating (comma coating) as a coating means, which can easily apply a shearing force to the coating liquid. The solid content of the support layer constituent liquid (the solid content of cellulose nanofibers, or the solid content of cellulose nanofibers and binder resin when a binder resin is included) is about 10% or less, about 7% or less, or about 5% or less. It can be. The lower limit of the solid content of the support layer constituent liquid is not particularly limited, but can be about 0.5% or more or about 1% or more. The support layer constituent liquid of the present disclosure includes both solutions and dispersions.

Use The laminated body of this indication is a laminated body which has high temperature tolerance which can endure shrinkage | contraction etc. with respect to the heat | fever in a solder reflow process, for example, and can be reduced in thickness. Therefore, the laminated body of this indication can be used for various uses with which about 200 degreeC or more, about 260 degreeC or more, or about 280 degreeC or more is provided under high temperature. The laminate of the present disclosure can be used at a considerably high temperature for a short time, and the upper limit is not particularly limited, but the upper limit of the use temperature is about 300 ° C. or less or about 350 It can be below ℃. The laminate of the present disclosure is excellent in workability such as punching and cutting, and can be used for applications that require processing such as punching and cutting. As specific applications based on these, for example, a solder reflow process, punching processing, and the like are applied, and it can be used for flexible (printed) circuit boards that are desired to be further thinner in recent years.

  The laminated body of this indication can mix | blend a conductive filler with a support layer and / or an adhesive layer, for example, In this case, in addition to said performance, it is excellent also in electrical grounding property etc. Since the laminate including the conductive filler has electrical conductivity, for example, when the laminate is used for a flexible circuit board, an electrical component, etc., electromagnetic noise generated from these, electromagnetic noise from the outside, etc. It can be reduced by being electrically grounded to a metal housing or the like through the laminate having conductivity, or the laminate can be replaced with a flexible circuit board, a substitute for a conductor used in an electrical component (for example, It can also be used as a reference conductor for a high-frequency transmission line.

  Examples of the conductive filler used in such applications include metal such as silver, platinum, gold, copper, nickel, palladium, aluminum, iron, solder, or metal alloy particles containing two or more of these metals. Inorganic particles such as silicon oxide and aluminum oxide, non-noble metal particles such as copper and nickel, resin particles, carbon particles, and the like, which are plated with a metal alloy containing two or more kinds of these metals or metal alloys containing these metals can be used.

  The conductive filler can be used in various sizes, and is not particularly limited. For example, (1) a conductive filler having a maximum diameter equal to or greater than the thickness of the laminate. When is added to the support layer, the filler is disposed above the surface of the laminate, so that the conductive path can be formed at least in the thickness direction of the laminate even if the amount of filler is small. (2) When a conductive filler having a maximum diameter equal to the thickness of the support layer or less than the thickness of the laminate is blended in the support layer, the size is equal to or less than the thickness of the pressure-sensitive adhesive layer. A conductive path is formed at least in the thickness direction of the laminate by blending the conductive filler having the maximum diameter of the pressure-sensitive adhesive layer in such an amount that the pressure-sensitive adhesive layer can exhibit conductivity in the thickness direction. Can do. (3) When a conductive filler having a maximum diameter less than the thickness of the support layer is blended in the support layer, the support layer is used in such an amount that the support layer can exhibit conductivity in the thickness direction. In addition, a conductive filler having a maximum diameter less than or equal to the thickness of the pressure-sensitive adhesive layer is added to the pressure-sensitive adhesive layer, and the pressure-sensitive adhesive layer is conductive in the thickness direction. The conductive path can be formed at least in the thickness direction of the laminate by blending the filler in the pressure-sensitive adhesive layer in an amount capable of exhibiting the properties. As the conductive filler blended in the support layer and / or the pressure-sensitive adhesive layer, at least two particles having different average particle diameters can be used in combination. With such a configuration, since the conductive filler having a small particle diameter is filled between the large particle diameters and filled in a close packed state, the conductivity is improved. The average particle diameter and particle size distribution of the conductive filler can be measured with an electron microscope, a laser diffraction light scattering apparatus, or the like. For example, when two fillers having different average particle sizes are used in combination, two peaks are observed in the particle size distribution in the material containing these fillers. Therefore, it is possible to confirm how many fillers having different average particle diameters are contained in the material by confirming the number of particle size distribution peaks in the material. Since the support layer constituent liquid containing cellulose nanofiber is excellent in thixotropy and can maintain a high viscosity state even if the solid content is low, this support layer constituent liquid is the above (1), (2) It can also be used for relatively large fillers that tend to settle, such as those used. In addition, the matter regarding the average particle diameter of the above conductive filler, a compounding quantity, etc. is employable similarly with respect to other fillers, such as a heat conductive filler.

  The following examples illustrate specific embodiments of the present disclosure, but the present disclosure is not limited thereto. All parts and percentages are by weight unless otherwise specified.

  The raw materials used in this example are shown in Table 1 below, and the blending ratios of various materials used for forming the pressure-sensitive adhesive layer and the support layer are shown in Table 2.

(Laminated sheet)
<Example 1>
A pressure-sensitive adhesive solution obtained by mixing 1 part by weight of a curing agent E-AX with an acrylic polymer using a monomer of 2-ethylhexyl acrylate / acrylic acid (90/10) (mass standard) is used as a release paper ( Coating with a notch bar coater (comma coater (registered trademark)) on a stripping ratio of 1: 3) and drying in an oven under conditions of 65 ° C. for 2 minutes and 110 ° C. for 2 minutes to a thickness of 8.5 μm An adhesive layer was formed. A support layer constituent liquid (CNF) is applied on the obtained pressure-sensitive adhesive layer with a notch bar coater (comma coater (registered trademark)) and dried in an oven at 65 ° C. for 2 minutes and at 120 ° C. for 2 minutes. Thus, a support layer having a thickness of 3 μm was formed. Subsequently, the above-mentioned pressure-sensitive adhesive solution is applied on the obtained support layer with a notch bar coater (Comma Coater (registered trademark)) and dried in an oven under conditions of 65 ° C. for 2 minutes and 110 ° C. for 2 minutes. To form a pressure-sensitive adhesive layer having a thickness of 8.5 μm, and further applying a release paper on the pressure-sensitive adhesive layer to obtain a double-sided pressure-sensitive adhesive laminate having a total thickness of 20 μm excluding the thickness of the release paper. Obtained.

<Comparative Example 1>
9079 which is a 50 μm-thick adhesive transfer tape (structure: release substrate / adhesive layer / release substrate) manufactured by 3M Japan Ltd. was used.

<Comparative example 2>
4597-30 which is a 30 μm-thick double-sided tape manufactured by 3M Japan Co., Ltd. (configuration: release substrate / adhesive layer / PET / adhesive layer / release substrate) was used.

  Table 3 shows the results of various tests shown below for the laminate of Example 1 and the double-sided tapes of Comparative Examples 1-2.

(Punching test)
Using punches with a round hole shape, the laminate and double-sided tape are punched out, “○” if they are punched out without problems, “×” indicating problems such as glue transfer to the punch, peeling of the peeling substrate, etc. Was determined.

(Adhesive strength test 1)
A 25 mm wide sample supported on a 65 μm thick copper clad laminate (CCL) was bonded to an epoxy-impregnated glass substrate, pressed once with a 2 kg roller, and left for 20 to 40 minutes. Thus, a measurement sample was prepared. After setting the measurement sample to a tensile tester (TENSILON (registered trademark)), the peel strength at 180 ° was measured at 23 ° C. and 300 mm / min in accordance with JIS Z 0237 (2000). The adhesive strength of the sample was determined by measuring the initial adhesive strength of the sample after pressing and standing and the adhesive strength after the following heat resistance test.

(Heat resistance test)
Samples of release substrate / laminate or double-sided tape / CCL configuration were passed once through a small solder reflow oven. As heating conditions in the oven, an atmosphere of about 260 ° C. was set to be maintained for about 20 seconds. After the heat resistance test, the case where there was no change in appearance was judged as “◯”, and the case where a defect such as curling or shrinkage occurred was judged as “x”.

  As can be seen from the results in Table 3, for example, the laminate of the present disclosure exhibits sufficient adhesive force even if it is thin, and has a support layer including cellulose nanofibers that supports the pressure-sensitive adhesive layer. Compared to the double-sided tape (Comparative Examples 1 and 2), it was confirmed that the processability such as punching and the heat resistance against heat of solder reflow processing were excellent.

(Conductive laminate)
<Example 2 to Example 8>
The adhesive solution is coated on the release substrate (BX9) with a notch bar coater (comma coater (registered trademark)) and dried in an oven at 65 ° C. for 2 minutes and at 110 ° C. for 2 minutes. A layer was formed. A support layer constituent liquid is applied on the obtained pressure-sensitive adhesive layer with a notch bar coater (comma coater (registered trademark)), and dried and supported in an oven at 65 ° C. for 2 minutes and at 130 ° C. for 2 minutes. A layer was formed. Subsequently, the pressure-sensitive adhesive solution was applied onto the obtained support layer with a notch bar coater (comma coater (registered trademark)), and dried in an oven under conditions of 65 ° C. for 2 minutes and 110 ° C. for 2 minutes. An adhesive layer was formed, and a release substrate (BKE) was further applied on the adhesive layer to obtain a double-sided adhesive conductive laminate. In addition, each material of the pressure-sensitive adhesive solution and the support layer constituting liquid used in forming the pressure-sensitive adhesive layer and the support layer in Examples 2 to 8, the thickness of the pressure-sensitive adhesive layer, the thickness of the support layer, and the laminate The total thickness (total thickness of the portion excluding the thickness of the release substrate) is shown in Table 4.
<Comparative Example 3>
9750 which is a 50 μm-thick conductive double-sided tape manufactured by 3M Japan Co., Ltd. (configuration: release substrate / adhesive layer / plated nonwoven fabric / adhesive layer / release substrate) was used.
<Comparative example 4>
AL25DC, which is an 85 μm-thick conductive double-sided tape manufactured by 3M Japan Ltd. (configuration: release substrate / adhesive layer / aluminum foil / adhesive layer / release substrate), was used.
<Comparative Example 5>
# 82600, a 5 μm-thick double-sided tape manufactured by 3M Japan Ltd. (configuration: release substrate / adhesive layer / PET / adhesive layer / release substrate) was used.

  About the laminated body of Examples 2-8 and the double-sided tape of Comparative Examples 3-5, the resistivity measurement test and the adhesive force test 2 which are shown below were done, and the result is shown in Table 4.

(Resistivity measurement test)
As shown in FIG. 2, a 10 mm × 10 mm laminate or double-sided tape sample 20 is placed between two 10 mm × 30 mm copper foils 3, and the copper foil 3 is pressure-bonded with a 2 kg roller. A sample for measurement was obtained. The resistance value of the sample was measured using a 4-probe digital milliohm meter (manufactured by Hioki Electric Co., Ltd .: HIOKI 3541).

(Adhesion test 2)
The conductive laminates of Examples 2 to 8 have a layer structure of release substrate (BKE) / adhesive layer / support layer / adhesive layer / release substrate (BX9). Let the base material (BX9) side be a back surface, and let a peeling base material (BKE) side be a surface. As the adherend, a SUS304BA plate whose surface was cleaned with Clean S manufactured by AS ONE Corporation was used. In Comparative Examples 3 to 5, it is difficult to distinguish between the front surface and the back surface, and the surface and the back surface are arbitrarily defined. It can be a result.

Measuring method of back surface The peeling base material (BKE) was peeled from the conductive laminate, and a 25 μm thick PET film was bonded. Next, after slitting to a width of 10 mm, the peeling substrate (BX9) is peeled off, the pressure-sensitive adhesive layer is bonded to the adherend, pressure-bonded using a 2 kg roller, and left for 20 to 40 minutes to produce a measurement sample. did. The measurement sample was set in a tensile tester (TENSILON (registered trademark)), and the peel strength at 180 ° was measured at a speed of 300 mm / min at room temperature.

Surface Measurement Method After slitting the conductive laminate to a width of 10 mm, the release substrate (BKE) was peeled off and the pressure-sensitive adhesive layer was bonded to the adherend. Next, the peeling substrate (BX9) is peeled off, and a 25 μm-thick PET film slit to a width of 15 mm is bonded to the adhesive layer, pressure-bonded using a 2 kg roller, and left for 20 to 40 minutes to prepare a measurement sample. did. The measurement sample was set in a tensile tester (TENSILON (registered trademark)), and the peel strength at 180 ° was measured at a speed of 300 mm / min at room temperature.

  As can be seen from the results in Table 4, the conductive laminate of the present disclosure can exhibit the same adhesiveness and conductivity as, for example, the conventional thick conductive double-sided tape used in Comparative Examples 3 and 4. Was confirmed. Therefore, it has been confirmed that the conductive laminate of the present disclosure can be sufficiently used as, for example, a component member of an electrical component that is desired to be thin.

DESCRIPTION OF SYMBOLS 1 Adhesive layer 2 Support layer 3 Copper foil 10 Laminated body 20 Sample

Claims (6)

A support layer;
A pressure-sensitive adhesive layer disposed on one or both sides of the support layer, and a laminate comprising:
A laminate in which the support layer includes cellulose nanofibers and has a thickness of 15 μm or less.   The laminate according to claim 1, wherein the support layer further contains a binder resin.   The laminated body of Claim 1 or 2 in which the said support layer and / or adhesive layer contain a filler.   The laminate according to claim 3, wherein the filler is a conductive filler. It is a manufacturing method of the layered product according to any one of claims 1 to 4,
Applying a pressure-sensitive adhesive solution to a release substrate and drying to form a pressure-sensitive adhesive layer;
On the pressure-sensitive adhesive layer, a support layer constituting liquid is applied and dried to form a support layer;
Optionally, applying a pressure-sensitive adhesive solution on the support layer and drying to form a pressure-sensitive adhesive layer. It is a manufacturing method of the layered product according to any one of claims 1 to 4,
Applying the adhesive solution to the first release substrate and drying to form a first release substrate comprising an adhesive layer;
The support layer constituent liquid is applied to the second release substrate and dried to form a second release substrate having the support layer, or the adhesive solution is applied to the second release substrate and dried. Forming a pressure-sensitive adhesive layer, applying and drying a support layer constituting liquid on the pressure-sensitive adhesive layer, and forming a second release substrate including the pressure-sensitive adhesive layer and the support layer;
The manufacturing method of a laminated body provided with the process of bonding the adhesive layer of a said 1st peeling base material, and the support layer of a said 2nd peeling base material.

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